It's been several years since I tried to install DBD::mysql on a 64 bit perl via ppm and at that time the 64 bit version was not ready for prime time and always failed. That may not be the case anymore.

You could try uninstalling it then reinstall it via cpan instead of ppm. Before you install the module, you'll need to install MinGW so that you'll have the proper compiler to build modules from source.